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Statistics Concepts And Controversies 10th Edition David S. Moore, William I. Notz - Solutions
9.4 HIV infection rates. According to a June 2015 report by the Centers for Disease Control and Prevention (CDC), one in eight Americans with HIV do not know that they are infected with the virus. The night the report was released, a news station reported “1 in 8 Americans do not know that they
9.3 Academic good standing. To be in good standing at college, a student needs to maintain a certain grade point average (GPA). Typically, a student who falls below 2.0 is put on academic probation for at least a semester. At a local college, administrators wanted to increase the GPA to remain in
8.33 Validity, bias, reliability. Give your own example of a measurement process that is valid but has large bias. Then give your own example of a measurement process that is invalid but highly reliable.
8.32 Where to work? Each year, Forbes magazine ranks the 2000 largest metropolitan areas in the United States in an article on the best places for businesses and careers. First place in 2017 went to Portland, Oregon. Portland was ranked 5th in 2016.Fourth place in 2017 went to Denver, Colorado.
8.31 The best earphones. You are writing an article for a consumer magazine based on a survey of the magazine’s readers that asked about satisfaction with mid-priced earphones for the iPod and iPhone. Of 1648 readers who reported owning the Apple in-ear headphone with remote and mic, 347 gave it
8.30 Testing job applicants. A company used to give IQ tests to all job applicants. This is now illegal because IQ is not related to the performance of workers in all the company’s jobs.Does the reason for the policy change involve the reliability, the bias, or the validity of IQ tests as a
8.29 Measuring pulse rate. You want to measure your resting pulse rate. You might count the number of beats in 5 seconds and multiply by 12 to get beats per minute.a. Consider counting the number of beats in 15 seconds and multiplying by 4 to get beats per minute. In what way will this improve the
8.28 Measuring crime. Twice each year, the National Crime Victimization Survey asks a random sample of households whether they have been victims of crime and, if so, the details.In all, nearly 160,000 people in about 90,000 households answer these questions per year. If other people in a household
8.27 Measuring crime. Crime data make headlines. We measure the amount of crime by the number of crimes committed or (better) by crime rates (crimes per 100,000 population). The FBI publishes data on crime in the United States by compiling crimes reported to police departments. The FBI data are
8.26 A recipe for poor reliability. Every month, the government releases data on “personal savings.” This number tells us how many dollars individuals saved the previous month.Savings are calculated by subtracting personal spending (an enormously large number) from personal income (another
8.25 Does job training work? To measure the effectiveness of government training programs, it is usual to compare workers’ pay before and after training. But many workers sign up for training when their pay drops or they are laid off. So the “before” pay is unusually low and the pay gain
8.24 Even more on bias and reliability. Exercise 8.22 gives five true values for lengths. A subject measures the first length (true length=2.9 inches) four times by eye. His measurements are 3.0 2.9 3.1 3.0 Suppose his measurements have a bias of +0.1 inches.a. What are the four random errors for
8.23 More on bias and reliability. The previous exercise gives five true values for lengths.A subject measures each length twice by eye. Make up a set of results from this activity that matches each of the descriptions below. For simplicity, assume that bias means the same fixed error every time
8.22 An activity on bias and reliability. Cut 5 pieces of string having these lengths in inches:2.9 9.5 5.7 4.2 7.6a. Show the pieces to another student one at a time, asking the subject to estimate the length to the nearest tenth of an inch by eye. The error your subject makes is measured value
8.21 An activity on bias. Let’s study bias in an intuitive measurement. Figure 8.3 is a drawing of a tilted glass. Reproduce this drawing on 10 sheets of paper. Choose 10 people: 5 men and 5 women. Explain that the drawing represents a tilted glass of water. Ask each subject to draw the water
8.20 Validity, bias, reliability. This winter I went to a local pharmacy to have my weight and blood pressure measured using a sophisticated electronic machine at the front of the store next to the checkout counter. Will the measurement of my weight be biased? Reliable? Valid?Explain your answer.
8.19 Testing job applicants. The law requires that tests given to job applicants must be shown to be directly job related. The Department of Labor believes that an employment test called the General Aptitude Test Battery (GATB) is valid for a broad range of jobs. As in the case of the SAT, blacks
8.18 Fighting cancer. Congress wants the medical establishment to show that progress is being made in fighting cancer. Here are some variables that might be used:Variable 1. Total deaths from cancer. These have risen sharply over time, from 331,000 in 1970, to 505,000 in 1990, and to 572,000 in
8.17 Measuring pain. There are 9 million enrollees in the Department of Veterans Affairs health care system. It wants doctors and nurses to treat pain as a “fifth vital sign,” to be recorded along with blood pressure, pulse, temperature, and breathing rate. Help out the VA:How would you measure
8.16 National well-being in the UK. Established in 2010, the “Measuring National Wellbeing”(MNW) program administered by the Office for National Statistics in the United Kingdom attempts to measure “how the UK is doing.” The MNW has questions that collect“both objective data (for example,
8.15 Measuring intelligence. One way “intelligence” can be interpreted is as “general problem-solving ability.” Explain why it is not valid to measure intelligence by a test that asks questions such as Who wrote “The Star-Spangled Banner”?Who won the last soccer World Cup?
8.14 Capital punishment. Between 1977 and 2017, 1465 convicted criminals were put to death in the United States. Here are data on the number of executions in several states during those years, as well as the estimated June 1, 2017, population of these states:State Population (thousands) Executions
8.13 Obesity. A 2017 Organisation for Economic Co-operation and Development(OECD) report provided the prevalence of obesity among adults in 36 countries. Based on information in the report, only 3.7% of adults in Japan are obese, compared to 22.3% in Turkey and 38.2% in the United States. Do these
8.12 Tough course? A friend tells you, “In the 7:30 A.M. lecture for Statistics 101, 9 students failed, but 20 students failed in the 1:30 P.M. lecture. The 1:30 P.M. prof is a tougher grader than the 7:30 A.M. prof.” Explain why the conclusion may not be true. What additional information would
8.11 Seat belt safety. The National Highway Traffic Safety Administration reports that in 2016, 11,282 occupants of motor vehicles who were wearing a restraint died in motor vehicle accidents and 10,428 who were not wearing a restraint died. These numbers suggest that not using a restraining device
8.10 Rates versus counts. Customers returned 40 cell phones to Verizon this spring, and only 15 to Best Buy next door. Verizon sold 800 cell phones this spring, while Best Buy sold 200.a. Verizon had a greater number of cell phones returned. Why does this not show that Verizon’s cell phone
8.9 Measuring a healthy lifestyle. You want to measure the “healthiness” of college students’ lifestyles. Give an example of a clearly invalid way to measure healthiness. Then briefly describe a measurement process that you think is valid.
8.8 Counting the unemployed? We could measure the extent of unemployment by a count(the number of people who are unemployed) or by a rate (the percentage of the labor force that is unemployed). The number of people in the labor force grew from 122 million in September 1988, to 138 million in
8.7 Comparing teaching assistants (TAs). Professor Holmes has two teaching assistants who grade homework for a Statistics 101 course. Professor Holmes gives each of the two teaching assistants a rubric (a clear scoring guide) for the TAs to use when they grade the assignments. Holmes gives each TA
8.6 Measuring athletic ability. Which of the following is not a valid measurement of athletic ability?a. Time (in seconds) to run a 100-meter dash.b. Number of times a person goes to the gym per week.c. Maximum weight (in pounds) a person can bench press.d. Number of sit-ups a person can do in 1
8.5 Weight at the doctor’s office. When you visit the doctor’s office, several measurements may be taken, one of which is your weight. A doctor’s office encourages patients to keep their shoes on to be weighed and promises to subtract 2 pounds for the weight of the patient’s shoes. Which of
8.4 What is the instrument of measurement? A college president is interested in student satisfaction with recreational facilities on campus. A questionnaire is sent to all students and asks them to rate their satisfaction on a scale of 1 to 5 (with 5 being the best). The instrument of measurement
8.3 Comparing marijuana use. According to the 2015–2016 National Survey on Drug Use and Health, among young adults aged 18–25 years, approximately 28.7% of young adults in Arizona, approximately 34.6% of young adults in Michigan, and approximately 47.5% of young adults in Colorado used
7.40 Tempting subjects. A psychologist conducts the following experiment: he measures the attitude of subjects toward cheating, then has them take a mathematics skills exam in which the subjects are tempted to cheat. Subjects are told that high scores will receive a $100.00 gift certificate and
7.39 Deceiving subjects. Students sign up to be subjects in a psychology experiment. When they arrive, they are placed in a room and assigned a task. During the task, the subject hears a loud thud from an adjacent room and then a piercing cry for help. Some subjects are placed in a room by
7.38 Surveys of youth. The Centers for Disease Control and Prevention, in a survey of teenagers, asked the subjects if they had ever had sexual intercourse. Males who said “Yes”were then asked, “That very first time that you had sexual intercourse with a female, how old were you?” and
7.37 Charging for data? Data produced by the government are often available free or at low cost to private users. For example, satellite weather data produced by the U.S. National Weather Service are available free to TV stations for their weather reports and to anyone on the Web.Opinion 1:
7.36 Telling the government. The 2010 census was a short-form-only census. The decennial long form was eliminated. The American Community Survey (ACS) replaced the long form in 2010 and will collect long-form-type information throughout the decade rather than only once every 10 years. The 2010 ACS
7.35 A right to know? Some people think that the law should require that all political poll results be made public. Otherwise, the possessors of poll results can use the information to their own advantage. They can act on the information, release only selected parts of it, or time the release for
7.34 Opinion polls. The congressional campaigns are in full swing, and the candidates have hired polling organizations to take regular polls to find out what the voters think about the issues. What information should the pollsters be required to give out?a. What does the standard of informed
7.33 The Stanford Prison Experiment. You may have seen or heard about the film The Stanford Prison Experiment (2015), which centered around Philip Zimbardo’s 1971 research on psychologically healthy individuals placed into a stressful situation, to answer the question about how context impacts
7.32 Henrietta Lacks. You may have heard of the book The Immortal Life of Henrietta Lacks by Rebecca Skloot (2010) or the Oprah Winfrey movie based on the book. Henrietta Lacks came from an impoverished tobacco farming family in Virginia. In 1951, when Henrietta was 31, she died at the Johns
7.31 AIDS trials in Africa. One of the most important goals of AIDS research is to find a vaccine that will protect against HIV. Because AIDS is so common in parts of Africa, that is the easiest place to test a vaccine. It is likely, however, that a vaccine would be so expensive that it could not
7.30 AIDS trials in Africa. Effective drugs for treating AIDS are very expensive, so most African nations cannot afford to give them to large numbers of people. Yet AIDS is more common in parts of Africa than anywhere else. A few clinical trials are looking at ways to prevent pregnant mothers
7.29 AIDS clinical trials. Now that effective treatments for AIDS are available, is it ethical to test treatments that may be less effective? Combinations of several powerful drugs reduce the level of HIV in the blood and at least delay illness and death from complications due to AIDS. But
7.28 The Willowbrook hepatitis studies. In the 1960s, children entering the Willowbrook State School, an institution for the mentally retarded, were deliberately infected with hepatitis. The researchers argued that almost all children in the institution quickly became infected anyway. The studies
7.27 Sham surgery? Clinical trials like the Parkinson’s disease study mentioned in Example 6 are becoming more common. One medical researcher says, “This is just the beginning.Tomorrow, if you have a new procedure, you will have to do a double-blind placebo trial.”Example 6 outlines the
7.26 Equal treatment. Researchers on depression proposed to investigate the effect of supplemental therapy and counseling on the quality of life of adults with depression. Eligible patients on the rolls of a large medical clinic were to be randomly assigned to treatment and control groups. The
7.25 Human biological materials. Long ago, doctors drew a blood specimen from you as part of treating minor anemia. Unknown to you, the sample was stored. Now researchers plan to use stored samples from you and many other people to look for genetic factors that may influence anemia. It is no longer
7.24 Not really anonymous. Some common practices may appear to offer anonymity while actually delivering only confidentiality. Market researchers often use mail, email, or Internet surveys that do not explicitly ask the respondent’s identity but contain hidden codes on the questionnaire that
7.23 https. Generally, secure websites use encryption and authentication standards to protect the confidentiality of web transactions. The most commonly used protocol for web security has been TLS, or Transport Layer Security. This technology is still commonly referred to as SSL (Secure Sockets
7.22 Sunshine laws. All U.S. states have open records laws, sometimes known as “Sunshine Laws,” that give citizens access to government meetings and records. This includes, for example, reports of crimes and recordings of 911 calls. Crime reports will include the names of anyone accused of the
7.21 Anonymous or confidential? A website is looking for volunteers for a research study involving methicillin-resistant Staphylococcus aureus (MRSA), a bacterial infection that is highly resistant to some antibiotics. The website contains the following information about the study: “The Alliance
7.20 Anonymous or confidential? The website for STDHELP.org contains the following information about one method offered for HIV testing: “The clinic will require you to provide some information that allows them to deliver your results. Typically a random numeric code is used for identification,
7.19 Anonymous or confidential? One of the most important nongovernment surveys in the United States is the General Social Survey (see Example 7 in Chapter 1). The GSS regularly monitors public opinion on a wide variety of political and social issues. Interviews are conducted in person in the
7.18 How common is HIV infection? Researchers from Yale University, working with medical teams in Tanzania, wanted to know how common infection with the AIDS virus is among pregnant women in that African country. To do this, they planned to test blood samples drawn from pregnant women.Yale’s
7.17 Students as subjects. Students taking Psychology 001 are required to serve as experimental subjects. Students in Psychology 002 are not required to serve, but they are given extra credit if they do so. Students in Psychology 003 are required either to sign up as subjects or to write a term
7.16 Undue influence? Undue influence in obtaining informed consent often occurs through an offer of an excessive or inappropriate reward or other overture in order to obtain compliance. Which of the following circumstances do you believe constitute undue influence? Explain why you answered the way
7.15 Coercion? The U.S. Department of Health and Human Services regulations for informed consent state that “An investigator shall seek such consent only under circumstances that provide the prospective subject or the representative sufficient opportunity to consider whether or not to participate
7.14 Is consent needed? In which of the circumstances below would you allow collecting personal information without the subjects’ consent? Why?a. A government agency takes a random sample of income tax returns to obtain information on the marital status and average income of people who identify
7.13 Informed consent. A researcher suspects that people who are abused as children tend to be more prone to severe depression as young adults. She prepares a questionnaire that measures depression and that also asks many personal questions about childhood experiences. Write a description of the
7.12 Institutional review boards. If your college or university has an institutional review board that screens all studies that use human subjects, get a copy of the document that describes this board (you can probably find it online). At larger institutions you may find multiple institutional
7.11 Who serves on the review board? Government regulations require that institutional review boards consist of at least five people, including at least one scientist, one nonscientist, and one person from outside the institution. Most boards are larger, but many contain just one outsider.a. Why
7.10 Minimal risk? You are a member of your college’s institutional review board. You must decide whether several research proposals qualify for less rigorous review because they involve only minimal risk to subjects. Federal regulations say that “minimal risk” means the risks are no greater
7.9 Ethics. Which of the following would be considered unethical in an experiment?a. Failure to obtain informed consent from subjects.b. Promising confidentiality to subjects but failing to protect it.c. Placing the interests of science over the interests of patients.d. All of the above.Most of the
7.8 Clinical trials. A clinical trial isa. an observational study held in a controlled, clinical environment.b. an experiment to study the effectiveness of medical treatments on actual patients.c. any study performed in a medical clinic.d. the review, by a court, of ethical violations in medical
7.7 Confidentiality? If, in a study, it is not possible to determine which subjects produced which data, we would saya. the subjects are anonymous.b. the study is confidential, but subjects are not anonymous.c. the study is double blind.d. the study is blind, but not double blind.
7.6 Informed consent. Informed consent should includea. consent by the subject, usually in writing.b. information, in advance, about the nature of a study.c. information, in advance, about possible risks.d. All of the above.
7.5 Institutional review board. The purpose of an institutional review board isa. to decide whether a proposed study will produce valuable information.b. to protect the rights of human subjects (including patients) recruited to participate in research activities.c. to decide whether a proposed
4. Federal regulations say that “minimal risk” means that the risks are no greater than“those ordinarily encountered in daily life or during the performance of routine physical or psychological examinations or tests.” Do you think this study qualifies as “minimal risk”?
3. The Center for Medicinal Cannabis Research (CMCR) at the University of California, San Diego will have just finished recruiting study participants when this textbook is published. Consider this research study and a research study on the health benefits of dark chocolate. For which study would
2. Based on the principles discussed in this chapter, would you consider the experiment to be ethical?
1. What does it mean to you for research to be ethical? How might that impact your answers to the following questions?
6.30 Political polarization and social media. On September 1, 2018, The Columbus Dispatch reported on a study about political polarization and social media. In this study, 901 Democrats and 751 Republicans were recruited. The Democrats were randomly divided into two groups. All were asked to follow
6.29 What do you want to know? The previous two exercises illustrate the use of statistically designed experiments to answer questions that arise in everyday life, such as how to improve sleep or what hamburger tastes best. Select a question of interest to you that an experiment might answer and
6.28 Five Guys versus In-N-Out Burgers. Five Guys and In-N-Out Burgers are often rated among the top hamburger chains in the country. Do consumers prefer the taste of a hamburger from Five Guys or from In-N-Out burgers in a blind test in which neither chain is identified? Describe briefly the
6.27 Better sleep? Is the number of times you awaken during the night affected by whether you have a glass of wine before bed and whether you have a snack before you go to bed?Describe briefly the design of an experiment with two explanatory variables, whether or not you have a glass of wine and
6.26 Algal blooms. Algal blooms have become a recurring problem on many American lakes. Among other things, they can cause damage to a person’s liver, kidneys, and nervous system. Phosphorus runoff from farms is one factor that contributes to algal blooms. Will inserting fertilizer into fields
6.25 Comparing weight-loss treatments. Twenty overweight males have agreed to participate in a study of the effectiveness of supplements that claim to produce weight loss.Four treatments are used: three supplements and a placebo. The three supplements are green coffee bean extract, raspberry
6.24 Technology for teaching statistics. The Brigham Young University statistics department performed randomized comparative experiments to compare teaching methods.One study compared two levels of technology for large lectures: standard (overhead projectors and chalk) and multimedia. The
6.23 Handwriting versus keyboard writing. Do people who write by hand have a better memory of what they write than those who write using a keyboard? To test this, researchers had 36 participants in a study write down a long list of words read out loud to them. They were then asked to put their list
6.22 Athletes take oxygen. We often see players on the sidelines of a football game inhaling oxygen. Their coaches think this will speed their recovery. We might measure recovery from intense exertion as follows: Have a football player run 100 yards three times in quick succession. Then allow three
6.21 Liquid water enhancers. Bottled water, flavored and plain, is expected to become the largest segment of the liquid refreshment market by the end of the decade, surpassing traditional carbonated soft drinks. Kraft’s MiO, a liquid water enhancer, comes in a variety of flavors and a few drops
6.20 Price change and fairness. A marketing researcher wishes to study what factors affect the perceived fairness of a change in the price of an item from its advertised price. In particular, does the type of change in price (an increase or decrease) and the source of the information about the
6.19 Ibuprofen and atherosclerosis. The theory of atherosclerosis (hardening and narrowing of the arteries) emphasizes the role of inflammation in the vascular walls. Since ibuprofen is known to possess a wide range of anti-inflammatory actions, it was hypothesized that it might help in the
6.18 Flu shots. A New York Times article reported a study that investigated whether giving flu shots to schoolchildren protects a whole community from the disease. Researchers in Canada recruited 49 remote Hutterite farming colonies in western Canada for the study. In 25 of the colonies, all
6.17 The best painkiller for children. A Washington Post article reported a study comparing the effectiveness of three common painkillers for children. Three hundred children, aged 6 to 17, were randomly assigned to three groups. Group A received a standard dose of ibuprofen. Group B received a
6.16 The placebo effect. A survey of physicians found that some doctors give a placebo to a patient who complains of pain for which the physician can find no cause. If the patient’s pain improves, these doctors conclude that it had no physical basis. The medical school researchers who conducted
6.15 Testing a natural remedy. The statistical controversy presented in this chapter discusses issues surrounding the efficacy of natural remedies. The National Institutes of Health has now begun sponsoring proper clinical trials of some natural remedies. The following is an example of one such
6.14 Beating sunburn with broccoli. Some recent studies suggest that compounds in broccoli may be helpful in combating the effects of overexposure to ultraviolet radiation.Based on these studies we hope to show that a cream consisting of a broccoli extract reduces sunburn pain. To do this, we
6.13 Blood-chilling and strokes. A Science News article reported a study of the effect of cooling the blood of stroke patients on the extent of recovery ninety days after the stroke. Researchers randomly assigned 58 severe-stroke patients to receive either tPA (the standard treatment for stroke) or
6.12 A high-fat diet prevents obesity? A Science News article reported that according to a study conducted by researchers at Hebrew University of Jerusalem, a high-fat diet could reset the metabolism and prevent obesity. In the study, researchers fed a group of mice a high-fat diet on a fixed
6.11 Bright bike lights. Will requiring bicyclists to use bright, high-intensity xenon lights mounted on the front and rear of the bike reduce accidents with cars by making bikes more visible?a. Briefly discuss the design of an experiment to help answer this question. In particular, what response
6.10 Eggs and cholesterol. An article in a medical journal reports on an experiment to see the effect of eating three whole eggs per day on cholesterol levels as compared to eating the equivalent amount of a yolk-free egg substitute. The article describes the experiment as a randomized,
6.9 Do antidepressants help? A researcher studied the effect of an antidepressant on depression. He randomly assigned subjects with moderate levels of depression to two groups.One group received the antidepressant and the other a placebo. Subjects were blinded with respect to the treatment they
6.8 Magic mushrooms. A Washington Post article reported that psilocybin, the active ingredient of “magic mushrooms,” promoted a mystical experience in two-thirds of people who took it for the first time, according to a study published in the online journal Psychopharmacology. The authors of the
6.7 Multivitamin supplements. To explore the effects of multivitamin supplements on health, you recruit 100 volunteers. Half are to take a multivitamin supplement daily. The other half are to take a placebo daily. Multivitamin supplements may have different effects on men and women because their
6.6 Reducing smoking. The Community Intervention Trial for Smoking Cessation asked whether a community-wide advertising campaign would reduce smoking. The researchers located 11 pairs of communities, with each pair similar in location, size, economic status, and so on. One community in each pair
6.5 Recycling. Which of the following is an important weakness of the experiment described in Exercise 6.4?a. This was not a matched pairs design.b. Because undergraduate students were used as subjects, the results may not generalize to all adults and all situations involving disposable items.c.
6.4 Recycling. Researchers recruited 60 undergraduate students, in exchange for course credit, for a study on the effect of recycling on how much wrapping paper subjects used to wrap a gift. The subjects were randomly assigned to one of two rooms. In one room there was a large recycling bin and in
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